PROJECT SUMMARY This T32 training program was established in 2014 to train the next generation of pre- and post- doctoral scholars in the prevention, treatment, and care of HIV and substance use among individuals involved with the criminal legal system (CLS). The training program is a partnership between the Columbia University School of Social Work (SSW) and the Mailman School of Public Health (MSPH), with strong support from longstanding partnerships with a number of research centers, schools, and departments at Columbia University. We propose to renew the program by continuing its unique position as the only NIDA-funded T32 program jointly run out of a school of social work and school of public health as well as the successful administration and activities; the renewal will maintain that last cycle’s emphasis on implementation and augment the program in: (1) community engagement, and (2) data science. The training program provides: (1) interdisciplinary research instruction and training for pre-doctoral students and post-doctoral fellows on the intersecting issues of substance use, HIV, implementation science, community engagement, and data science with the CLS and CLS-involved populations; and (2) hands-on, mentored experience conducting independent research in the program’s banner themes. This program is designed to strengthen the pool of researchers by increasing the diversity of academic backgrounds—e.g., social work, public health, medicine, sociology, political science, anthropology—and those from underrepresented populations—e.g., underrepresented minorities (URM), people with disabilities, individuals from disadvantaged backgrounds. The participating faculty are scientific leaders in the fields of CLS, HIV, substance use, implementation science, community engagement, and data science, with strong track records of support from NIH; they are also well-qualified to provide training, as evidenced by their strong records of mentorship of pre- and post-doctoral early career scholars. At capacity, the program supports 4 pre-doctoral students and 4 post-doctoral trainees per year (a total of 6-8 pre-doctoral trainees and 8-10 post-doctoral trainees in the renewal period). Thus, the program will add a substantial number of highly qualified new scholars to the field focusing on HIV, substance use, implementation science, community engagement, and data science among CLS-involved populations. Dr. Nabila El-Bassel and Dr. Lisa Metsch will continue to serve successfully as PIs/Co-Directors for the proposed training program, which provides an opportunity for two noted and distinguished scientists to collaborate and lead this initiative. They contribute over 30 years each of experience in the program’s banner themes, shepherded impressive growth in success in the program’s most recent cycle of funding, and will provide continuity in leadership for the proposed renewal.